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Did they make it look easy or what? ULA, your move.
Oh, and the payload (a Falcon capsule with ISS supplies) was delivered into a perfect orbit, solar cells deployed, on schedule to dock. Carrying, among other things, Bigelow's expandable module for testing. https://en.wikipedia.org/wiki/Bigelo...ctivity_Module
I bet there's some good times being had in Hawthorne right now...
What I find amazing is the fact that the Merlin 1D engine (nine on the stage, just one used for the landing) is too powerful to actually make the rocket hover. At its lowest thrust, it adds upwards velocity, so there's a hair-raising maneuver involved. SpaceX calls it a "hover-slam", some use "suicide burn" - in effect, the computer starts out with the position of the target, the position of the rocket, and the rocket's velocity and orientation.
It then precomputes what the rocket position, velocity and attitude will be on closest approach to the barge, then computes a rocket burn (throttle, duration and gimbal angle) that will put the rocket at vertical, with vertical and horizontal speed at 0, no roll, pitch or yaw, just as the altitude reaches 0. As the descent takes place, that solution is kept updated.
And then the computer executes that burn at the determined time. Done.
There's no option for correction, hovering into a better position or anything of the sort. They get one shot, and the math has to check out.
What I find amazing is the fact that the Merlin 1D engine (nine on the stage, just one used for the landing) is too powerful to actually make the rocket hover. At its lowest thrust, it adds upwards velocity, so there's a hair-raising maneuver involved. SpaceX calls it a "hover-slam", some use "suicide burn" - in effect, the computer starts out with the position of the target, the position of the rocket, and the rocket's velocity and orientation.
It then precomputes what the rocket position, velocity and attitude will be on closest approach to the barge, then computes a rocket burn (throttle, duration and gimbal angle) that will put the rocket at vertical, with vertical and horizontal speed at 0, no roll, pitch or yaw, just as the altitude reaches 0. As the descent takes place, that solution is kept updated.
And then the computer executes that burn at the determined time. Done.
There's no option for correction, hovering into a better position or anything of the sort. They get one shot, and the math has to check out.
The amount of fuel and LOX burn is amazing. I wonder how much mass loss after the first stage is landed. The low center of gravity certainly helps with the landing. Our companies sells many components to SpaceX. Once the landing becomes a regular event, I wonder how that will affect our sales. It is exciting nonetheless.
How is free-fall handled before the burn? Is a parachute deployed at any time, otherwise how are they decreasing terminal velocity prior to the burn? I think the technology is amazing, especially considering the obstacles that have to be overcome.
How is free-fall handled before the burn? Is a parachute deployed at any time, otherwise how are they decreasing terminal velocity prior to the burn? I think the technology is amazing, especially considering the obstacles that have to be overcome.
No parachutes, but 2 separate 3-engine burns - a "boostback" burn to put the stage on the right trajectory, and a "reentry burn" to slow it down - then it's free fall guided by grid fins until the final burn.
No parachutes, but 2 separate 3-engine burns - a "boostback" burn to put the stage on the right trajectory, and a "reentry burn" to slow it down - then it's free fall guided by grid fins until the final burn.
Some clever people involved.
That sounds more reasonable than free fall followed by a final burn. I did notice the guidance fins. Excellent technological achievement.
Holy flippin' cow! That is awesome! They did indeed make it look easy. That must have been the most difficult thing imaginable to do.
But can they do it again? And again and again etc? Probably.
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